How to Make a Boot Disk for OS X Mavericks (10.9)

Even though Apple has not yet officially released OS X Mavericks, but it's sure that Apple will change some installation package structures and you won't be able to make an OS X Mavericks USB install drive before. You will need another way to make a bootable OS X Mavericks USB install drive.

Build a Bootable USB Installer for The OS X Mavericks

1. First you need to show hidden file and implement the command in the Terminal:
defaults write com.apple.Finder AppleShowAllFiles YES && killall Finder

2. Download the installer in App Store and you can find "Install OS X 10.9". Right click the app and choose "Show Package Content".

3.Enter Contents/SharedSupport and you will see a file named InstallESD.dmg. Double click and mount it.

4. Under the mounted disk directory you will see a BaseSystem.dmg file.

5. Open "Disk Utility" and restore BaseSystem.dmg to your USB drive. Here source disk should be BaseSystem.dmg and target disk should be the USB drive.

6. after restoring, open the USB volume(default name "OS X Base System") and go to System/Installation. Here you will see an alias for package similar like shortcut with a small arrow label. Delete it.

7. Copy all the folders in the mounted InstallESD directory (same where you found the BaseSystem.dmg file) to System/Installation folder in the USB drive. This is to replace the deleted file in the USB drive with the real package in the mounted InstallESD volume.

8. Done. Now the USB should be bootable. Connect the USB with your Mac and run it by holding down the option key(Alt). Select "to boot in the USB drive" in the disk launching interface.

9. If you want to hide the hidden files again the go back to the first step and choose No.

Now you can boot up from your newly bootable disk of OSX 10.9. Let us know if this works for you by sounding off in the comments!